Support "varsIgnorePattern" on no-redeclare rule

ESLint version: 3.2.2

The problem I’m using no-unused-vars with "varsIgnorePattern": "_+" in order to allow this syntax (in React):

render() {
  const { children, beforeSubmit: _, onSuccess: __, onFailure: ___, ...props } = this.props
  return <form {...props} onSubmit={this.submit} onReset={this.reset}>{children}</form>
}

As you see I’m using the ES6 rest parameters syntax to create a shallow copy of the this.props object while omitting certain properties, so I can use the JSX spread operator to pass them all in one go. This is necessary because React will throw an error when passing non-standard attributes to an HTML element. However, some of these props are not being used in the scope of this function, so ESLint would complain about that. Right now I use the varsIgnorePattern option on no-unused-vars to allow any variable that consists of only underscores and assign each of the unused props to _, __, ___ etc. As you see this gets ugly. I would rather just alias them all to _, but I can’t right now because no-redeclare would complain about that.

Suggestion I suggest adding support for "varsIgnorePattern" to no-redeclare, so it can be configured like this:

"no-redeclare": [2, { "varsIgnorePattern": "_" }],

Background: I also program in Scala, in which it is common to use _ do denote “something is here but I don’t care what it’s called” (among other uses).

I’d be happy to implement this if I know my PR has a chance of being accepted.

[sleepycat]

@kaicataldo This should be reopened IMO. @ghengeveld is making an useful enhancement request and even offering to implement, and @platinumazure seems to support this. I personally would love to see this option added.

[ghengeveld]

I think you’re confusing my code for a regular object literal, while what I’m doing is a destructuring assignment. This really is a variable declaration, so no-redeclare is correct. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Assigning_to_new_variable_names